Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho, Brazil

C.L.M Forjaz,A Prista,J.A Oliveira,J.A.S Rezende,J.A.R Maia,T Bartholomeu,L Basso,G Tani

doi:10.1590/s0100-879x2012007500141

Abstract

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h2), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h2 = 0.37 ± 0.10, P < 0.05; diastolic BP: h2 = 0.39 ± 0.09, P < 0.05; TPA: h2 = 0.24 ± 0.09, P < 0.05). Significant genetic (rg) and environmental (re) correlations were detected between systolic and diastolic BP (rg = 0.67 ± 0.12 and re = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (re = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.

Highlights

Epidemiological data have shown an inverse relationship between regular physical activity (PA) and blood pressure (BP) [1,2]
We investigated SBP and diastolic BP (DBP) phenotypes, as well as total PA (TPA)
The main findings of the present study were that: a) low, but significant genetic factors explained the variation of SBP and DBP, as well as TPA; b) SBP and DBP cross-trait genetic and environmental influences were significant; c) no such influences were evident for SBP and TPA, while a strong tendency (P = 0.057) to a significant cross-trait environmental correlation was observed between DBP and TPA

Summary

Introduction

Epidemiological data have shown an inverse relationship between regular physical activity (PA) and blood pressure (BP) [1,2]. The linking agents of this association are not completely understood and may be due, in part, to common environmental and genetic factors. Taken, PA and BP levels have been shown to be influenced by genetic as well as by environmental factors [3,4,5,6,7]. The magnitude of genetic influences on these phenotypes varies. Previous review articles have shown that heritability (h2 - the fraction of the total phenotypic variance that is accounted for by genetic factors) for systolic (SBP) and diastolic BP (DBP) ranged from 14 to 68 and from 6 to 62%, respectively [7], while for PA, heritability ranged from 6 to 62% [6]. The main explanations for this wide variation are differences in population structures in genetic and environmental terms, sample sizes, experimental designs, estimation techniques for h2, and phenotype assessment techniques [6,7]

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